Question: $ { {3} \times \left[\begin{array}{rr}{1} & {-1} \\ {1} & {0} \\ {2} & {-2}\end{array}\right] = {?} } $
Answer: To multiply a matrix by a number, multiply each item of the matrix by the number. ${\left[\begin{array}{rr}{3}\times{1} & {3}\times{-1} \\ {3}\times{1} & {3}\times{0} \\ {3}\times{2} & {3}\times{-2}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{3} & {-3} \\ {3} & {0} \\ {6} & {-6}\end{array}\right]}$